Silicon carbide: A new positron moderator

Observation of copious positron re-emission from crystalline 6H-SiC, with no pretreatment and without the need for ultra-high-vacuum conditions, suggests that this material may form the basis of an important new moderator for the production of monoenergetic positrons. Its positron work function is measured to be -3.0 +/- 0.2 eV. Its electrical characteristics point to SiC as a prime candidate for development as a field-assisted positron moderator, producing moderately intense slow-positron beams in laboratory-based systems and enabling a new generation of positron experimentation.